This invention relates to a heat exchanger with a distribution device for uniformly distributing a medium to a plurality of exchanger tubes.
Generally the efficiency of a heat exchanger is affected not only by heat transfer of an outer fluid flowing outside of a plurality of tubes of the heat exchanger but also by heat transfer of an inner fluid flowing inside of the tubes. In particular, flow distribution of the inner fluid has a great influence. By way of example, consideration will be made about an evaporator as the heat exchanger. A mixed-phase refrigerant as a mixture of a gas-phase refrigerant and a liquid-phase refrigerant is introduced into a plurality of tubes of the evaporator. Due to the difference in inertial force, the gas-phase and the liquid-phase refrigerants are not uniformly distributed in the mixed-phase refrigerant supplied to the evaporator. In other words, the mixed-phase refrigerant inevitably has different void ratios at various points in a flow path. In the present specification, a void ratio is defined as a ratio of the volume of the gas-phase refrigerant to the volume of the mixture of the gas-phase and the liquid-phase refrigerants. Under the circumstances, the liquid-phase refrigerant is concentrated to a particular tube while the gas-phase refrigerant is concentrated to another tube. This brings about nonuniform temperature distribution within the evaporator. As a result, the efficiency of the heat exchanger is deteriorated.
For example, a conventional heat exchanger is disclosed in Japanese Unexamined Patent Publication (JP-A) No. 155194/1992. In the conventional heat exchanger, however it is impossible to uniformly distribute the refrigerant to a plurality of exchanger tubes, as will later be described.